Someone who was against the Dakota Access Pipeline apparently vandalized the World War II memorial in Washington, the National Park Service said Tuesday.

Spokesman Mike Litterst said someone spray-painted the North Dakota section of the memorial. A photo provided by the park service showed the phrase “#NoDAPL” was written in paint.

The Standing Rock Sioux tribe has been fighting along with other tribes and environmental groups to stop the completion of the $3.8 billion pipeline, saying it would threaten the water supply for millions of people. Supporters say the pipeline is a safer way to move oil than trucks and trains.

Obama said government agencies will let the situation “play out for several more weeks and determine whether or not this can be resolved in a way that I think is properly attentive to the traditions of the First Americans.”